1. Field of the Invention
The present invention relates to the support of multi-radio coexistence in a mobile station using a broadband wireless access system, and more particularly, to a method for improving throughput of a broadband wireless access system and another wireless communication system.
2. Discussion of the Related Art
In a broadband wireless access system based on the IEEE 802.16e system, a sleep mode for minimizing power consumption of a mobile station is supported.
The mobile station requests a base station to transition to a sleep mode via a sleep mode request (MOB_SLP-REQ) message if downlink traffic is not transmitted from the base station to the mobile station during a predetermined time. Accordingly, the base station allows the sleep mode entry of the mobile station via a sleep mode response (MOB_SLP-RSP) message.
In the sleep mode, the operation of the mobile station is performed by the repetition of a sleep interval and a listening interval. A method of utilizing the IEEE 802.16e system in the listening interval and allowing the use of another wireless communication system such as Bluetooth or WiFi to provide coexistence of a time sharing scheme in the sleep interval is suggested.
FIG. 1 shows the support of coexistence of WiMax and Bluetooth if each of the listening interval and the sleep interval has a length of two frames.
In the related art, the support of multi-radio coexistence of an IEEE 802.16-based M-WiMAX mobile station with the IEEE 802.15-based Bluetooth or IEEE 802.11-based WiFi allows the Bluetooth or WiFi to use a portion of the listening interval and the sleep interval of the 802.16-based M-WiMAX mobile station and allows the M-WiMAX mobile station to communicate with an M-WiMAX base station in only a portion of the listening interval.
As shown in FIG. 1, in order to support coexistence with the Bluetooth, the WiMAX mobile station and the base station do not transmit/receive data to each other such that data is exchanged via the Bluetooth during the sleep interval after the mode of the mobile station is triggered to the sleep mode in which each of the listening interval and the sleep interval has two frames. In addition, even in the listening interval of the sleep mode, the WiMAX mobile station can transmit/receive data to/from the base station via a downlink subframe of a first frame and an uplink subframe of a second frame. The base station does not schedule an uplink subframe of the first frame and a downlink subframe of the second frame of the listening interval, for the Bluetooth.
It is possible to prevent Bluetooth data loss and throughput deterioration by allowing the Bluetooth to use the portion of the listening interval in the sleep mode of the mobile station.
FIG. 2 is a view showing the support of coexistence if each of a listening interval and a sleep interval has a length of one frame.
In FIG. 2, a mobile station receives a DL-MAP and a UL-MAP of nth, n+2th, and n+4th frames. Another communication system such as Bluetooth or WiFi is used in an interval in which the mobile station does not receive the DL-MAP and the UL-MAP (Non-802.16 Tx Interval).
The total throughput of a time sharing scheme cannot exceed 1, and throughput deterioration may occur due to the interruption of a transmission or reception operation which has been performed, that is, fragmentation, in a time boundary.
In addition, in the interference between the Bluetooth and the WiMAX, generally, the uplink transmission of the WiMAX mobile station has a significant influence on the data reception of the Bluetooth. In other words, the downlink data reception of the WiMAX mobile station may be influenced by the data transmission of the Bluetooth. In detail, if the reception quality of the WiMAX signal having a predetermined level or more is maintained, the data transmission of the Bluetooth does not have an influence on the downlink data reception of the WiMAX mobile station.
However, if the WiMAX channel quality falls to less than the predetermined level, the data transmission of the Bluetooth gives interference to the downlink data reception of the WiMAX mobile station and thus the WiMAX downlink throughput may deteriorate.